Mayor Greg Nickels will be looking far beyond Seattle when he takes up one of the most ambitious political challenges of his career this weekend.

Nickels will try to persuade the U.S. Conference of Mayors, which represents 1,183 cities, to do what the federal government has refused to do and endorse the Kyoto treaty goals for reducing greenhouse-gas emissions.

Known for plugging potholes and pleasing developers during his first term, Nickels has turned to the far reaches of Earth’s atmosphere and found an issue that’s gained him national and international attention. The New York Times, BBC, Manila Bulletin and Belfast Telegraph are among the news organizations that have noted Nickels’ campaign to get American mayors to support the Kyoto goals, endorsed by 141 nations earlier this year, but rejected by the Bush administration on the grounds that it could hurt the U.S. economy.

Nickels says he wants to show state and federal leaders there’s political support for such a position, noting, “This is a national debate we can’t really sidestep.”

Detractors, though, suspect Nickels is trying to promote himself and bash Bush.

Nickels has enlisted 161 cities from 37 states to sign a pledge to cut emissions.

While most of those cities are in coastal “blue” states that vote Democratic, the list includes exceptions such as Las Vegas, Laredo, Texas, and Gary, Ind., where a perpetual haze of pollution created by the steel industry hangs over the city.

“These industries are shrinking for a lot of us,” said Mayor Scott King of Gary. “We’re focusing on the economic transition that has to take place. Either we start now or compromise our ability to compete.”

Still, Nickels is expecting stiff opposition at the mayors meeting in Chicago, which starts tomorrow. It’s likely to come mostly from “red state” mayors, said Steve Nicholas, the mayor’s top environmental adviser, though some Democratic cities such as Chicago, Philadelphia and Detroit have not joined Nickels’ effort.

Plus, mayors Nickels believed were on board might be defecting. That’s the case with Mayor Richard Ward of Hurst, Texas.

Hurst, a Republican, had signed Nickels’ Kyoto initiative in April, but now says he will vote against it because he now thinks it’s a “Democratic political ploy.”

Other skeptics say Nickels’ campaign is a grandstanding play with little political risk in leafy, left-leaning Seattle. And they say it wouldn’t do much to counter global warming trends even if successful.

Nickels, who does not face well-funded opposition in his re-election bid this year, says his focus on global warming has local roots. At its core, the problem is a dramatic increase of greenhouse-gas emissions, which come mainly from burning fossil fuels and the release of carbon dioxide.

Scientists expect these emissions to reach a dangerous level around the middle of this century. And they threaten to raise global temperatures to a point where polar ice caps would melt, seas would rise and cities might be submerged.

“There really is no debate within the scientific community. It’s really a matter of political will to tackle it,” said Philip Mote, a research scientist at the University of Washington and the state climatologist.

California’s Republican Gov. Arnold Schwarzenegger declared last week “the debate is over” as he called for the Golden State to dramatically cut its greenhouse-gas emissions.

Here in Washington, the warming effect is seen in rising temperatures and declining mountain snowpacks.

At first, Nickels said he was not distressed by these trends. “I think like most Americans I sort of said, ‘So what? It would be nice if it were a few degrees warmer.’ “

But then he learned more about how Seattle’s water and electricity supplies could be hurt by a shrinking snowpack. In meetings with Seattle’s water and electricity department chiefs, Nickels said he heard repeated forecasts for below-average snowpack. Eventually he said he realized “we’re never going to get average again.”

Politically, the first step in fighting climate change is meeting the goals of the Kyoto pact, which set a 2012 goal for an industrialized country such as the U.S. to reduce emissions by 7 percent below 1990 levels.

The hope, Mote said, is that Kyoto would lead to heightened awareness and more countries agreeing to cut more emissions.

Critics say it doesn’t take much courage for Nickels to take a pro-Kyoto stand. For starters, Seattle can increase its population and job base in a greener way than most cities because its electricity comes from a city-owned utility that draws most of its energy from clean water power.

“The only reason they can do any of this is because we dammed the rivers for hydropower. Otherwise the city would be burning a lot more stuff for power,” said Eugene Wasserman, president of the North Seattle Industrial Association.

Wasserman sees Nickels’ climate initiative as a political stunt.

Ward, the Texas mayor, agreed and said he thought Nickels’ effort was intended to embarrass Bush.

“Maybe Mayor Nickels wants publicity to run for governor,” said Ward. “I think this is a Hillary Clinton, Ted Kennedy, John Kerry strategy.”

Even if Nickels succeeds in reducing Seattle emissions to Kyoto levels, it would amount to an insignificant change in global conditions.

“We know the only way to stability is to cut emissions by 70 percent,” climatologist Mote said. “You have to imagine a whole series of international treaties like Kyoto over the next 50 years.”

Meanwhile, the Puget Sound region’s single biggest source of emissions is transportation, with cars accounting for most of the problems. And regional emissions are expected to increase 21 percent over 1990 levels by 2010, according to the Puget Sound Clean Air Agency. “What is the city going to do?” Wasserman asks. “Ban cars?”

Nickels acknowledged that the Kyoto goals are “modest.” But the path to deeper emissions cuts has to start somewhere, and Nickels said mayors can “take on issues that haven’t yet reached the boiling point at the national level and literally make it safe for national and state leaders to then take the issue up.”

City Councilman Richard Conlin, who’s known as a champion of environmental issues and a Nickels rival, praised the initiative.

“I think visibility and publicity is substance. It’s substantive because it’s keeping awareness up and getting the issue more visibility,” Conlin said.

Heidi Wills agreed. The former councilwoman, who led the council to adopt Kyoto targets for city government in 2001, offered nothing but praise for Nickels. “I think the mayor is taking it a step further than the council by contacting other cities. It is brilliant. The mayor is filling a vacuum. There’s just not been leadership on a national stage,” she said.

In Chicago, Nickels will present his pro-Kyoto resolution to two different committees on Saturday. If it passes by a simple majority in either committee, it will go to the full conference for a floor vote Monday. Nicholas, the mayor’s environmental adviser, said he anticipates close committee votes.

If he comes up short in Chicago, Nickels says he will carry on the fight.

He expects meaningful results from a Green Ribbon Commission on Climate Protection he appointed earlier this year.

Nickels said he hopes the commission will come up with recommendations that “really begin to fundamentally change how we fuel our economy with carbon.” Most of the world’s pollution comes from cities, and they can cut greenhouse-gas emissions in many ways, ranging from planting trees to relying more on solar, wind and nuclear power.

He said he won’t drop his efforts because “we have put ourselves on the line to produce and we’ve created a community of cities that will expect that kind of leadership from us, and ask us why it’s lacking, if it’s lacking.”